Allen left the team's morning shootaround Saturday early with a trainer while wearing wraparound black glasses.
Allen is the Grizzlies' primary defender on Kevin Durant, and the central reason why the Thunder star is shooting just 41 percent in the series.
The Grizzlies already will be without Zach Randolph, who was suspended Friday after throwing a punch at Thunder center Steven Adams during Oklahoma City's 100-84 Game 6 victory in Memphis. The Grizzlies found out just before getting on their plane that they'd be without their star big man.
Joerger would not comment on the suspension.
"Fair or unfair, that's the situation that we're in," Grizzlies center Marc Gasol said.
Point guard Mike Conley is dealing with a strained right hamstring, but he plans on playing and went through shootaround. However, he admits he will be limited.
Conley's backup, Nick Calathes, is also suspended because of a violation of the league's anti-drug policy.
"It feels around the same, the pain is still there," Conley said. "I'm going to go as hard as I can for as long as I can."
"The Thunder are great, but we've beaten them before, we've beaten them in here before," Joerger said. "We believe we can win. If not, we wouldn't walk out there tonight."